Investigation of Carrier Transport and Leaching Mechanisms in Chalcopyrite Mineral

Chalcopyrite (CuFeS₂) is a critical mineral and a primary source of copper, which is essential for modern technology in various fields including, electronics, renewable energy, and heat transfer mechanisms. However, the extraction of copper from chalcopyrite has been hindered by its extremely slow dissolution rate with conventional metallurgical processes. Previous studies suggest that the leaching behavior may be connected to the carrier transport properties of chalcopyrite, but experimentation results have been inconsistent. Previous studies vary from one another, which makes it difficult to draw definitive conclusions. In this study, we conducted a comprehensive and systematic investigation into the charge transport properties of various chalcopyrite samples characterized by distinct morphological configurations. The transport properties were analyzed using Hall-effect measurements at temperatures ranging from 135 K to 335 K. The chalcopyrite samples were prepared in various purities and forms, including washed v unwashed powder concentrate, natural mineral, and synthetic chalcopyrite. Our synthetic samples were created with a defined phase transport method; controlled solidification kinematics and melt characteristics were used to create these samples. Our Hall-effect measurement conditions were refined during our experimentation, these include number of sample trials, time duration between sampling, applied probe current, and temperature stability. We correlated the charge transport results with their leaching behavior. The results indicate that Hall measurements exhibit considerable sensitivity, showing significant variation in response to changes in our measurement conditions. Despite that, we identified the optimal experimental conditions and established relationships between mobility, resistivity, and bulk concentration measurements. Our preliminary results suggest that the transport properties indeed affect the leaching behavior. Leached sample concentrate exhibited mobility measurements between 8.0×10^-1 to 2.0×10⁰ cm²/Vs and resistivity measurements ranging from 1.6 to 8.0 Ωcm. Our work has the potential to advance the field of sustainable copper extraction, thereby contributing to improved material criticality efforts.